ly2kutd1552さん、
I'm afraid I have nothing to add to my initial response to your first question. I wasn't even certain about that one, so anything else I say would be pure guessing, which isn't all that helpful
Looking over the examples, ついに to me seems like it relates to something that was planned in some way - either something that someone was trying to do and finally succeeded, or something that someone was trying to get someone else to do. Or, with a negative verb, something that someone had planned to do but ended up not doing. It doesn't seem so common to use ようやく for things that are planned (although I do see at least one example where that is the case). More often it seems to relate to positive outcomes that someone has no control over. I'm not so sure about where やっと or やっとにさ fit into that, though.
小狼